Definition and Classification
Megafloods are paleofloods (past floods) that involved rates of water flow larger than those in the historical record. They are studied through the sedimentary deposits and the erosional and constructional landforms that individual megafloods have created. Floods that are known to us through historical descriptions are mostly related to meteorological events, such as heavy rains, rapid melting of snowpacks, or combination of these. In the geological past of the Earth, however, geological research has shown that much larger events have occurred. In the case of outburst floods, such floods are typically linked to the collapse of the barrier forming a lake. They fall in the following classification according to the mechanism responsible:
- Collapse of glacier dams that impound proglacial lakes (Missoula Floods).
- Rapid erosion, melting of ice sheets (jökulhlaups).
- Collapse of earthen barriers (landslides or glacial moraines).
- Collapse of volcanic dams created by lava flows, lahars, or pyroclastic flows.
- Overtopping of earthen or rock barriers
- Lake overtopping (e.g., Lake Bonneville).
- Ocean spilling over a dividing ridge into a landlocked basin (e.g., Zanclean flood, Black Sea flood). A smaller scale example would be the Pantai Remis landslide.
Read more about this topic: Outburst Flood
Famous quotes containing the word definition:
“Mothers often are too easily intimidated by their children’s negative reactions...When the child cries or is unhappy, the mother reads this as meaning that she is a failure. This is why it is so important for a mother to know...that the process of growing up involves by definition things that her child is not going to like. Her job is not to create a bed of roses, but to help him learn how to pick his way through the thorns.”
—Elaine Heffner (20th century)